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Background Cardiovascular magnetic resonance (CMR) is an important diagnostic test used in the evaluation of patients with heart failure (HF). However, the demographics and clinical characteristics of those undergoing CMR for evaluation of HF are unknown. Further, the impact of CMR on subsequent HF patient care is unclear. The goal of this study was to describe the characteristics of patients undergoing CMR for HF and to determine the extent to which CMR leads to changes in downstream patient management by comparing pre-CMR indications and post-CMR diagnoses. Methods We utilized the Society for Cardiovascular Magnetic Resonance (SCMR) Registry as our data source and abstracted data for patients undergoing CMR scanning for HF indications from 2013 to 2019. Descriptive statistics (percentages, proportions) were performed on key CMR and clinical variables of the patient population. The Fisher’s exact test was used when comparing categorical variables. The Wilcoxon rank sum test was used to compare continuous variables. Results 3,837 patients were included in our study. 94% of the CMRs were performed in the United States with China, South Korea and India also contributing cases. Median age of HF patients was 59.3 years (IQR, 47.1, 68.3 years) with 67% of the scans occurring on women. Almost 2/3 of the patients were scanned on 3T CMR scanners. Overall, 49% of patients who underwent CMR scanning for HF had a change between the pre-test indication and post CMR diagnosis. 53% of patients undergoing scanning on 3T had a change between the pre-test indication and post CMR diagnosis when compared to 44% of patients who were scanned on 1.5T (p < 0.01). Conclusion Our results suggest a potential impact of CMR scanning on downstream diagnosis of patients referred for CMR for HF, with a larger potential impact on those scanned on 3T CMR scanners.

Although accurate risk prediction is essential in guiding treatment decisions in primary prevention of atherosclerotic cardiovascular disease, the accuracy of the Framingham Risk Score (recommended by a Canadian guideline) and the Pooled Cohort Equations (recommended by US guidelines) has not been assessed in a large contemporary Canadian population. Our primary objective was to assess the calibration and discrimination of the Framingham Risk Score and Pooled Cohort Equations in Ontario, Canada. We conducted an observational study involving Ontario residents aged 40 to 79 years, without a history of atherosclerotic cardiovascular disease, who underwent cholesterol testing and blood pressure measurement from Jan. 1, 2010, to Dec. 31, 2014. We compared predicted event rates generated by the Framingham Risk Score and the Pooled Cohort Equations with observed event rates at 5 years using linkages from validated administrative databases. Our study cohort included 84 617 individuals (mean age 56.3 yr, 56.9% female). Over a maximum follow-up period of 5 years, we observed 2162 (2.6%) events according to the outcome definition of the Framingham Risk Score, and 1224 (1.4%) events according to the outcome definition of the Pooled Cohort Equations. The predicted event rate of 5.78% by the Framingham Risk Score and 3.51% by the Pooled Cohort Equations at 5 years overestimated observed event rates by 101% and 115%, respectively. The degree of overestimation differed by age and ethnicity. The C statistics for the Framingham Risk Score (0.74) and Pooled Cohort Equations (0.73) were similar. The Framingham Risk Score and Pooled Cohort Equations significantly overpredicted the actual risks of atherosclerotic cardiovascular disease events in a large population from Ontario. Our finding suggests the need for further refinement of cardiovascular disease risk prediction scores to suit the characteristics of a multiethnic Canadian population.

Implantable cardioverter-defibrillators (ICDs) cause banding artifacts around areas of B0 inhomogeneity in conventional steady-state free precession (SSFP) cine sequences. Alternatively, high-bandwidth gradient-recalled echo (GRE) cine sequences can be used to minimize artifacts in the myocardium. In this study, we assessed the bias and interobserver variability in cardiac volumes and ejection fractions between GRE cines in acquired in the presence of ICDS and ground-truth SSFP cines (without ICDs present) in a population of healthy volunteers. Further, a small cohort of ICD patients was recruited and scanned to demonstrate clinical feasibility. High-bandwidth GRE cine was performed in 11 healthy volunteers with taped ICDs mimicking clinical implants. After the ICD was removed, ground-truth SSFP cine was performed. Two observers separately assessed image quality metrics and contoured the cine images to return cardiac volumes and ejection fractions. Nine patients with an ICD were also scanned with the GRE cine protocol before contrast administration; data were contoured by two observers and analyzed for interobserver agreement. In the healthy volunteer dataset, no statistically significant differences were found when comparing volumes or ejection fractions between sequences (p > 0.05). Statistically significant differences were found when comparing right ventricular ejection fraction (RVEF) (p = 0.009) and right ventricular end-systolic volume (p = 0.029) between observers, with no other significant interobserver differences. The interobserver variability of patient left ventricular ejection fraction and RVEF data was 3–4%, with lower image quality metrics for patient scans than volunteer scans. GRE cine imaging in healthy volunteers with taped ICDs demonstrated good agreement with SSFP cine, but increased interobserver variability. In patients, reducing the breath-hold duration caused a decrease in image quality, with GRE cine imaging in patients with ICDs demonstrating poorer image quality and greater interobserver variability than in healthy volunteer studies. Future work is needed to improve GRE cine image quality in patients with ICDs to reduce interobserver variability and improve clinical confidence. [Display omitted]

Cardiac MRI is the gold standard for evaluating left ventricular myocardial mass (LVMM), end-systolic volume (LVESV), end-diastolic volume (LVEDV), stroke volume (LVSV), and ejection fraction (LVEF). Deep convolutional neural networks (CNNs) can provide automatic segmentation of LV myocardium (LVF) and blood cavity (LVC) and quantification of LV function; however, the performance is typically degraded when applied to new datasets. A 2D U-net with Monte-Carlo dropout was trained on 45 cine MR images and the model was used to segment 10 subjects from the ACDC dataset. The initial segmentations were post-processed using a continuous kernel-cut method. The refined segmentations were employed to update the trained model. This procedure was iterated several times and the final updated U-net model was used to segment the remaining 90 ACDC subjects. Algorithm and manual segmentations were compared using Dice coefficient (DSC) and average surface distance in a symmetric manner (ASSD). The relationships between algorithm and manual LV indices were evaluated using Pearson correlation coefficient (r), Bland-Altman analyses, and paired t-tests. Direct application of the pre-trained model yielded DSC of 0.74 ± 0.12 for LVM and 0.87 ± 0.12 for LVC. After fine-tuning, DSC was 0.81 ± 0.09 for LVM and 0.90 ± 0.09 for LVC. Algorithm LV function measurements were strongly correlated with manual analyses (r = 0.86–0.99, p < 0.0001) with minimal biases of −8.8 g for LVMM, −0.9 mL for LVEDV, −0.2 mL for LVESV, −0.7 mL for LVSV, and −0.6% for LVEF. The procedure required ∼12 min for fine-tuning and approximately 1 s to contour a new image on a Linux (Ubuntu 14.02) desktop (Inter(R) CPU i7-7770, 4.2 GHz, 16 GB RAM) with a GPU (GeForce, GTX TITAN X, 12 GB Memory). This approach provides a way to incorporate a trained CNN to segment and quantify previously unseen cardiac MR datasets without needing manual annotation of the unseen datasets.

Background Appropriate use criteria (AUC) have been developed in response to growth in cardiac imaging utilization and concern regarding associated costs. Cardiac computed tomography angiography (CCTA) has emerged as an important modality in the evaluation of coronary artery disease, however its appropriate utilization in actual practice is uncertain. Our objective was to determine the appropriate utilization of CCTA in a large quaternary care institution and to compare appropriate utilization pre and post publication of the 2013 AUC guidelines. We hypothesized that the proportion of appropriate CCTA utilization will be similar to those of other comparable cardiac imaging modalities and that there would be a significant increase in appropriate use post AUC publication. Methods We employed a retrospective cohort study design of 2577 consecutive patients undergoing CCTA between January 1, 2012 and December 30, 2016. An appropriateness category was assigned for each CCTA. Appropriateness classifications were compared pre- and post- AUC publication via the chi-square test. Results Overall, 83.5% of CCTAs were deemed to be appropriate based on the AUC. Before the AUC publication, 75.0% of CCTAs were classified as appropriate whereas after the AUC publication, 88.0% were classified as appropriate ( p  < 0.001). The increase in appropriate utilization, when extrapolated to the Medicare population of the United States, was associated with potential cost savings of approximately $57 million per year. Conclusions We report a high rate of appropriate use of CCTA and a significant increase in the proportion of CCTAs classified as appropriate after the AUC publication.

ObjectivesTo identify patient, physician and geographic level factors that are associated with variation in initial stress testing strategy in patients evaluated for chest pain.DesignRetrospective cohort study.SettingPopulation-based study of patients undergoing evaluation for chest pain in Ontario, Canada between 1 January 2011 and 31 March 2018.Participants103 368 patients who underwent stress testing (graded exercise stress testing (GXT), stress echocardiography (stress echo) or myocardial perfusion imaging (MPI)) following evaluation for chest pain.Primary and secondary outcome measuresTo identify the patient, physician and geographic level factors associated with variation in initial test selection, we fit two separate 2-level hierarchical multinomial logistic regression models for which the outcome was initial stress testing strategy (GXT, MPI or stress echo).ResultsThere was significant variability in the initial type of stress test performed, with approximately 50% receiving a GXT compared with approximately 36% who received MPI and 14% who received a stress echo. Physician-level factors were key drivers of this variation, accounting for up to 59.0% of the variation in initial testing. Physicians who graduated medical school >30 years ago were approximately 45% more likely to order an initial stress echo (OR 1.45, 95% CI 1.17 to 1.80) than a GXT. Cardiovascular disease specialists were approximately sevenfold more likely to order an initial MPI (OR 7.35, 95% CI 5.38 to 10.03) than a GXT. Patients aged >70 years were approximately fivefold more likely to receive an MPI (OR 4.74, 95% CI 4.42 to 5.08) and approximately 26% more likely to receive a stress echo (OR 1.26, 95% CI 1.15 to 1.38) than a GXT.ConclusionsWe report significant variability in initial stress testing strategy in Ontario. Much of that variability was driven by physician-level factors that could potentially be addressed through educational campaigns geared at reducing this variability and improving guideline adherence.

Rates of cardiovascular disease among people with diabetes have declined over the last 20–30 years. To determine whether First Nations people have experienced similar declines, we compared time trends in rates of cardiac event and disease management among First Nations people with diabetes and other people with diabetes in Ontario, Canada. We conducted a retrospective cohort study of patients aged 20 to 105 years with diabetes between 1996 and 2015, using linked health administrative databases. Outcomes compared were the annual incidence of each admission to hospital for myocardial infarction and heart failure, and death owing to ischemic heart disease. Management indicators were coronary revascularization and prescription rates for cardioprotective medications. Overall rates and annual percent changes were compared using Poisson regression. Incidence rates for all cardiac outcomes decreased over the study period. The greatest relative annual decline among First Nations men and women were observed in ischemic heart disease death (4.4%, 95% confidence interval [CI] 3.0 to 5.9) and heart failure (5.4%, 95% CI 4.5 to 6.4), respectively. Among other men and women, the greatest annual declines were seen in ischemic heart disease death (6.3%, 95% CI 6.1 to 6.5 and 7.3%, 95% CI 7.1 to 7.6, respectively). However, all absolute cardiac event rates were higher among First Nations people (p < 0.001). Coronary artery revascularization procedures and prescriptions for cardioprotective medications increased among First Nations people, while only prescriptions increased among other people. Over the last 20 years, the incidence of cardiac events has declined among First Nations people with diabetes, but remains higher than other people with diabetes in Ontario. For continued reductions in incidence, future efforts need to recognize First Nations people’s unique social and cultural determinants of health.

A critical chemotherapeutic complication is cardiotoxicity, often leading, in time, to heart failure. In this work, we developed a novel animal protocol using magnetic resonance (MR) imaging and electrophysiology (EP) tests, designed to detect subtle structural and functional changes associated with myocardial damage in sub-chronic phases post-chemotherapy. A weekly dose of doxorubicin (DOX) was injected in four juvenile swine throughout a four-week plan, using an intravenous approach that mimics the treatment in cancer patients. We performed cardiac MR imaging as follows: in all four pigs pre-DOX; at 1 and 5 weeks post-DOX in a group of two pigs; and, at 1 and 9 weeks post-DOX in the other two pigs, using Cine imaging to assess ejection fraction (EF) and late gadolinium enhancement to quantify collagen density in the left ventricle. Additionally, X-ray-guided voltage mapping and arrhythmia tests were conducted in the group at 9 weeks post-DOX and in a healthy pig. Tissue samples were collected for histology. The results showed that EF decreased from ~46% pre-DOX to ~34% within the first 9 weeks post-DOX. This decline in LV function was explained by a gradual increase in collagen density, especially noticeable at week 9 post-DOX as derived from MRI analysis. Furthermore, ventricular fibrillation was induced via rapid pacing at 9 weeks post-DOX, most likely caused by fibrotic patches identified in voltage maps, as confirmed by MRI and collagen-sensitive histological stains. Overall, our novel preclinical protocol was able to reveal key signs of potentially-irreversible tissue changes, along with electrical remodeling and arrhythmia risk in the early months following DOX therapy. Future work will include more datasets to statistically power the study, and will use the protocol to test cardioprotective strategies.

Transcatheter aortic valve implantation with the self-expandable CoreValve (CV) and the balloon-expandable Edwards SAPIEN (ES) bioprostheses has been widely used for the treatment of severe aortic stenosis. However, a direct comparison of the hemodynamic results associated with these 2 prostheses is lacking. The aim of the present study was to compare the hemodynamic performance of both bioprostheses. A total of 41 patients who underwent transcatheter aortic valve implantation with the CV prosthesis were matched 1:1 for prosthesis size (26 mm), aortic annulus size, left ventricular ejection fraction, body surface area, and body mass index with patients who underwent transcatheter aortic valve implantation with the ES prosthesis. Doppler-echocardiographic data were prospectively collected before the intervention and at hospital discharge, and all examinations were sent to, and analyzed in, a central echocardiography core laboratory. The mean transprosthetic residual gradient was lower (p = 0.024) in the CV group (7.9 ± 3.1 mm Hg) than in the ES group (9.7 ± 3.8 mm Hg). The effective orifice area tended to be greater in the CV group (1.58 ± 0.31 cm2 vs 1.49 ± 0.24 cm2, p = 0.10). The incidence of severe prosthesis–patient mismatch was, however, similar between the 2 groups (effective orifice area indexed to the body surface area ≤0.65 cm2/m2; CV 9.8%, ES 9.8%, p = 1.0). The incidence of paravalvular aortic regurgitation was greater with the CV (grade 1 or more in 85.4%, grade 2 or more in 39%) than with the ES (grade 1 or more in 58.5%, grade 2 or more in 22%; p = 0.001). The number and extent of paravalvular leaks were greater in the CV group (p <0.01 for both comparisons). In conclusion, transcatheter aortic valve implantation with the CV prosthesis was associated with a lower residual gradient but a greater rate of paravalvular aortic regurgitation compared to the ES prosthesis. The potential clinical consequences of the differences in hemodynamic performance between these transcatheter heart valves needs to be addressed in future studies.